Magnetically operable float switch



il 5, 1967 R. PERL 3,356,304

MAGNETICALLY OPERABLE FLOAT SWITCH Filed Feb. 25, 1966 INVENTOR RICHARDL. PERL BY MZQQMfiM ATTORNEYS United States Patent 3,356 804MAGNETICALLY OPERZXBLE FLOAT SWITCH Richard L. Perl, Mansfield, Ohio,assignor to The Tappan Company, Mansfield, Ohio, a corporation of OhioFiled Feb. 25, 1966, Ser. No. 530,018 2 Claims. ('Cl. 20084) ABSTRACT OFTHE DISCLOSURE A float switch for dishwashers and the like in which amagnet is carried on the center section of a float device betweenrelatively enlarged end sections open at the bottom. The float devicemoves within a housing containing a magnetically operated switch, withthe float device hav ing ribs at its outer surfaces and feet at thebottom to preclude locking to the housing.

This invention relates to a control device for automatic dishwashers andthe like and, more particularly, to a control which will afford positiveprotection against overflow in the water fill operations of the machine.

While the desirability of such protection has been generally appreciatedand some dishwashed models are available in which such a control isincorporated, the majority now being supplied are not so equipped andflooding is still a fairly common experience. In some areas, localregulations require a siphon break in the discharge line from the washerand the configuration usually involves a substantial bend with lateralrestriction of the line. Blockage at such a restricted portion by foodparticles and the like often occurs, with overflow as a result of theincomplete draining in machines the controls of which are insensitive tothe water actually filling the tub. Some dishwashers can overflow simplyby uninformed or inadvertent manipulation of the control knob, and thismalfunction is usually found to occur in the least expensive models,where the added cost of providing an automatic water fill limitingdevice would necessarily be a very significant factor. The devices whichare now available for the purpose are reasonably complicated and quiteexpensive, which is believed to be the primary reason for the relativelylimited use at the present time notwithstanding the obvious desirabilityand added user attraction and satisfaction of such a feature.

It is, therefore, a principal object of the present invention to providea control device for overflow protection in an automatic dishwasher andthe like which is of extremely simple construction, free of anypractical maintenance problems, and yet so inexpensive as to present anegligible cost factor in the production of such a machine.

Another object is to provide such a control which can very readily beaccommodated in conventional automatic dishwasher designs, with furthereconomic advantage on this account.

It is another object of the present invention to provide such a controldevice in which a magnetic float of special configuration is employedfor switch actuation responsive to the level of water within the tub ofthe machine, with this device thereby having a minimum of parts and notrequiring maintenance attention.

Other objects and advantages of the present invention will becomeapparent as the following description proceeds.

To the accomplishment of the foregoing and related ends the invention,then, comprises the features hereinafter fully described andparticularly pointed out in the claims, the following description andthe annexed drawing setting forth in detail a certain embodiment of theinvention, this being indicative, however, of but one of the variousWays in which the principle of the invention may be employed.

"Ice

In said annexed drawing:

FIG. 1 is a rear elevation of a magnetic float control switch inaccordance with the present invention;

FIG. 2 is a vertical cross section of the assembly on the planeindicated by the line 22 in FIG. 1; and

FIG. 3 is a perspective view of the magnetic float used in the device.

Referring now to the drawing in detail, the new control device comprisesa housing or cover generally designated by reference numeral 10 made ofa material, such as nylon, which will not be adversely affected byexposure to the ordinary detergents and the like used in automaticdishwashers. This cover, which can be inexpensively molded as a singlepiece, is box-like, with an open back, top wall 11, bottom wall 12,front wall 13 and side walls 14.

The cover is further formed with an interior intermediate sectiondesignated generally by reference numeral 15 which depends from the topwall 11 and extends rearwardly transversely from the front wall 13. Thissection comprises an upper cylindrical portion 16 the rear end of whichis in the plane of the open back of the cover, with an opening 17extending completely therethrough and continuing through the front wall13. A second cylindrical portion 18 of slightly larger diameter isbeneath the upper portion 16 and is oriented in generally the samemanner. However, this lower section is of such greater length as toproject noticeably beyond the back plane of the cover. Moreover, whilethis portion 18 is also hollow, it is open at the rear and closed at thefront.

As represented in FIG. 2, the device is placed within the tub of thedishwasher against the rear wall 19 of the tub and resting on the bottomwall 20. The cover 10 is securely held by means of a single attachingscrew 21 inserted from the front through the centered transverse upperopening 17 and threadably through the rear tub wall 19. The lowerportion 18 of the intermediate transverse section receives aconventional reed switch 22, shown as comprising a pair of normallyclosed blade contacts within a glass envelope, and having a pair ofwires 23 which extend therefrom for appropriate connection in thecontrol circuit for the dishwasher. The rear tub wall must of course beprovided with an opening 24 to accommodate the projection of the sectionor portion 18 therethrough to theexterior, and such passage is sealed bya metal washer 25 and elastomeric ring 26 encircling the section at theinside of the wall.

The cover 10 is provided with lower corner openings 27 which permit thewater supplied to the tub to enter the cover, with a pair of ventopenings 28 provided at the front upper corner for free escape of air.The assembly and mounting is accordingly such that water filling the tubof the washer will enter and rise to the same level within the cover.

A specially designed magnetic float designated generally by referencenumeral 29 is freely enclosed by the cover and this device comprises abody, again preferably molded in one piece of nylon, having invertedopen bottomed box sections 30 at its respective ends and a middlesection 31 of considerably reduced height with respect to the commonbottom plane. This middle section defines a generally rectangular traycarrying a permanent magnet 32. As will be most clearly evident fromFIG. 1, the magnetic float is dimensioned so that the end sections 30are respectively at the sides of the depending intermediate coversection 15 and the magnet 32 is thus disposed directly below the portionin which the reed switch 22 is housed. The float body is also formedwith a number of vertical ribs 33 projecting from the outer walls topreclude locking or sticking to the cover by fluid tension and extendingbelow the bottom plane to provide feet which serve to space the bodyfrom the bottom wall 12 of the cover when the float is resting on thelatter, for example, when no water is present;

It will now be apparent that as water is supplied to the tub and theinterior of the cover, the float 29 will be buoyed and rise with thewater, whereby the magnet is caused to approach the switch section. Whenthe float reaches a predetermined elevation, the magnetic attractionwill be suificient to open the contacts and this switch opening is ofcourse applied to the conventional control circuit in such manner toterminate the water supply, for example, by actuation of the inlet valveto closed condition. The geometry of the float provides a low center ofgravity and still allows the magnet to effectively reach the switch, thecontrol level being established and maintained with accuracy andreliability. The open bottom form of the float permits easy molding andof course without any sealing problems. It will also be appreciated thatthis control will provide trouble-free operation and generally clearlymeets the objectives stated hereinabove. The unit is particularly to becontrasted in this respect to pressure and weight responsive controldevices which have been made available for comparable protection, butonly at considerably more cost and complication of construction. Suchconventional devices, furthermore, do not provide the desired controlwith tolerance comparable to that which can be maintained in the newmagnetic float switch.

The cover preferably has a closed bottom as shown to permit the controlto be used in dishwashers of different and widely varying tub bottomconfigurations, and the water inlet holes are sized to render thecontrol insensitive to agitation of the water in the tub. Such inletholes are thus large enough to permit Water to flow freely into and outof the cover, but not large enough to allow any interior wave effects.The air outlet holes are also of predetermined size so that they arelarge enough to prevent surface tension of the liquid from trapping theair, but not large enough to admit too much water and soil.

The reed switch can be held in place by cementing or by a suitablefastener, such as a spring clip, and it is also possible to utilize apress fit. In this last assembly, fins could be provided along theinterior of the switch receiving socket for better engagement with theswitch envelope. With a relatively reversed configuration, for example,with the switch at the bottom and the float of inverted U-shape to placethe magnet at the top thereof rather than the bottom as shown, anormally open magnetic switch can be used which is held closed by themagnet and released when the float is raised by the water.

In the illustrated preferred embodiment, only the single screw fasteneris needed for attachment, but it might be desired in some installationsto employ a hinge attachment which would permit the cover to be swungupwardly to expose the interior for cleaning. The device will of coursenormally be designed to be inoperative as long as the water level in thetub does not exceed the anticipated level.

Other modes of applying the principle of the invention may be employed,change being made as regards the details described provided the featuresstated in any of the following claims or the equivalent of such beemployed.

I, therefore, particularly point out and distinctly claim as myinvention:

1. A water fill control for automatic dishwashers, comprising a housinghaving top, bottom and side walls adapted to be mounted within adishwasher tub adjacent the bottom thereof, said housing being providedwith an upper air vent and a lower opening for free flow of water intoand out of the housing with filling and draining of the tub, a magneticswitch fixed in an upper portion of the housing in sealed relation andadapted to control the supply of water'to the tub, a float movablewithin the housing, said float being raised and lowered withcorresponding change in the level of water in the housing and relativeto said switch, and a permanent magnet carried by said float, the magnetbeing effective to actuate the switch when raised to a predeterminedheight by the float, with the float having a center section at which themagnet is carried and hollow end sections of substantially greaterheight, the switch being located above said center section, and thefloat further provided with feet and ribs at its outer surfaces topreclude locking to the housing by fluid tension.

2. A control as set forth in claim 1, wherein the end sections of thefloat are open at the bottom.

References Cited UNITED STATES PATENTS 2,233,235 2/1941 Witthaus 73-3192,399,111 4/1946 George 73.322.5 X 2,646,067 7/1953 Smith 200-84 X3,149,753 9/1964 Forsyth 20084 X 3,163,731 12/1964 Lyden 200-84 BERNARDA. GILHEANY, Primary Examiner. H. A. LEWITTER, Assistant Examiner.

1. A WATER FILL CONTROL FOR AUTOMATIC DISHWASHERS, COMPRISING A HOUSINGHAVING TOP, BOTTOM AND SIDE WALLS ADAPTED TO BE MOUNTED WITHIN ADISHWASHER TUB ADJACENT THE BOTTOM THEREOF, SAID HOUSING BEING PROVIDEDWITH AN UPPER AIR VENT A LOWER OPENING FOR FREE FLOW OF WATER INTO ANDOUT OF THE HOUSING WITH FILLING AND DRAINING OF THE TUB A MAGNETICSWITCH FIXED IN AN UPPER PORTION OF THE HOUSING IN SEALED RELATION ANDADAPTED TO CONTROL THE SUPPLY OF WATER TO THE TUB, A FLOAT MOVABLEWITHIN THE HOUSING, SAID FLOAT BEING RAISED AND LOWERED WITHCORRESPONDING CHANGE IN THE LEVEL OF WATER IN THE HOUSING AND RELATIVETO SAID SWITCH, AND A PERMANENT MAGNET CARRIED